The diagnostic utility of putrescine, spermidine, cadaverine, and spermine as cancer biomarkers was investigated. Levels of these polyamines in the serum of patients displaying a variety of malignancies were measured using a new polyamine analyzer (Technicon). The presence, in serum, of unidentified polyamines with retention times close to those for cadaverine and spermidine makes interpretation of concentrations of these two polyamines equivocal. Levels of spermine are usually very low, while those of putrescine do not appear to reflect accurately the status of malignancy. Twenty-four hour urine collections were made from cancer patients and polyamines were determined in these samples. Preliminary data indicate that, using samples of urine, the resolution of peaks representative of the polyamines is considerably improved, relative to that obtained with serum samples. Studies are underway to determine if a reproducible relationship exists between the disease status of cancer patients and levels of individual polyamines from urine samples.